I had my right kidney removed 7 years ago due to a congenital deformity, and I continue to have pain where the kidney had been. Could this be from scar tissue? Sometimes (right now) I cannot even function because it is so painful. What could this be and should I return to my kidney doctor?

It is a good idea to see your kidney doctor for this pain.
if you had a partial kidney removal you may have a rare complication like aneurysm or arterio-venous fistula.
Pain can be also related to scar tissue changes and even a case of incisional hernia should be considered (hernia at the incision site may develop soon after the original surgery, or at any time thereafter, and a bulge may not be evident at the hernia site initially and pain may be the only early symptom).

I've have the same issues and its becoming a nuisance,it's been 1 yr since my surgery and I need help figuring out why I have a large buldge and serious pain.
Have you figured out,if so I could use some info